A passenger conveyor typically includes a series of passenger platforms which are driven in an endless path between horizontally spaced landings. The most common types of passenger conveyors are escalators and horizontal walkways. In the case of escalators, the platforms are steps which are driven between an upper landing and a lower landing to facilitate the movement of individuals, cargo, and the like. Passenger conveyors also usually include hand rails which are movable along and supported by opposite sides of a main frame of the conveyor.
Individual passenger platforms normally are circuitously connected by a pair of drive chains which extend along opposite sides of the passenger conveyor and engage a powered sprocket assembly mounted at at least one end of the conveyor to effect continuous sequential movement of the platforms between the upper and lower landings. The platforms extend laterally across the conveyor between the opposite main frame sides to define a step band; that is, a spatial envelope between the upper and lower landings and between the opposite handrails through which the platforms travel The platforms, which move passengers toward an off-load landing, travel "above" the sprocket assembly and define an upper step band, while the inverted platforms which return to the on-load landing travel "below" the sprocket assembly and define a lower step band.
A prime mover, such as an electric motor, commonly is used to drive the platforms. In order to transfer power between the motor and the sprocket assembly, a transmission frequently is provided
In a known passenger conveyor transmission construction, a conveyor is driven by a motor through a worm gear which engages a laterally extending output shaft. Worm drives are bulky and inefficient, and additionally require a chain connection between the last stage of the transmission and a sprocket assembly.
Other types of generally known transmissions directly engage a sprocket assembly and are mounted between the upper step band and the lower step band inboard the opposite sides of the conveyor frame Such a design requires that the upper step band and the lower step band be adequately spaced a vertical distance sufficient to accommodate the transmission therebetween. Modern building design considerations limit the overall packaging space allowed for a passenger conveyor and associated drive mechanism and thus limit the utility of existing direct drive transmissions.
The present invention is directed toward overcoming the problems set forth above by providing an efficient, compact power transmission for a passenger conveyor which does not adversely impact the overall packaging requirements of the conveyor.